text: #include <stdio.h>
  #include <setjmp.h>
  #include <stdlib.h>
  #include <string.h>
  
  int bottom, top;
  
  int run(int y) {
    // confuse stack
    char *s = (char *)alloca(100);
    memset(s, 1, 100);
    s[y] = y;
    s[y / 2] = y * 2;
    volatile int x = s[y];
    top = (int)alloca(4);
    if (x <= 2) return x;
    jmp_buf buf;
    printf("setjmp of %d\n", x);
    if (setjmp(buf) == 0) {
      printf("going\n");
      x += run(x / 2);
      longjmp(buf, 1);
    }
    printf("back\n");
    return x / 2;
  }
  
  int main(int argc, char **argv) {
    int sum = 0;
    for (int i = 0; i < argc * 2; i++) {
      bottom = (int)alloca(4);
      sum += run(10);
      // scorch the earth
      if (bottom < top) {
        memset((void *)bottom, 1, top - bottom);
      } else {
        memset((void *)top, 1, bottom - top);
      }
    }
    printf("%d\n", sum);
    return sum;
  }
  